Shave a 5.5 Snyder head to a 6

[marc silva]

Should I shave a 5.5 snyder head to a 6 or just buy a 6? If it can be done without trouble how much do I go? I’m collecting parts to build a Burtz block. Any opinions? Thanks, Marc

[denniskliesen]

A New Burtz head will be 6.5:1 and you won’t have to shave it.

[ronn]

Great question Mark. I am looking forward to hearing the responses from the motorheads.......


Dennis makes a good point, if you want to go a notch higher........

[Bob-A]

I've got a copy of an old message that I printed from off of the original FordBarn somewhere. I believe it says that a Snyder 5.5 head milled 20 thousands of an inch. Would bring the CR up to 5.9 and it does make a difference in the performance of the motor.



Bob-A

[nkaminar]

There is more to a head design than just the compression ratio. The 5.5 head from Snyders has a V shaped combustion chamber and the 6.0 head has more of an oval shape. The 6.0 head is more like the high performance Harley Davidson flathead heads. I don't know, but the 6.0 head may have more turbulence and better breathing. I have not seen the Burtz head but that will be interesting to view. For comparison, below is a high performance head for a Briggs and Stratton engine. Note the squish area (the piston does not protrude like a Model A) and the carved out area for better breathing.

[Bob Bidonde]

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If you take 0.020" off of the head, will there be enough clearance over the pistons to accommodate:
>Carbon buildup;
>Piston protrusion above the block deck.
I found out the hard way that a remaining 0.010"" deep piston relief in the head was not enough. Another problem I ran into was leveling the head for the cut. The machine setup has to have the piston relief surfaces level, not the deck surface of the head.

Without seeing some dyno data on the power & torque differences between a 5.5:1 head and a 6:1 head, I would be hesitant to cut the 5.5:1 head.

Have you looked improving the carburation for better breathing?

[marc silva]

Thank you that was a concern I had regarding the shape of the combustion chamber. I’m thinking just because you up the compression doesn’t mean it will be the right way to go about it. The 5.5 is designed to be just that and a 6 is designed to be what it is performance wise…just wasn’t sure. Marc

[marc silva]

I haven’t looked into the carburetion aspects yet. The motor I’m running right now runs so good I hate to mess with it. If after I get this new motor assembled and running discover it is short on fuel delivery or performance I will surely be looking into it.

[CarlG]

12 years ago, before Snyder came out with the 6.0 head, there were some suppliers that were taking the Snyder 5.5 head and shaving it so that it became a 6.0. I tried to buy one, but they said that they were having too many problems and were only offering the 5.5 as Snyder made them.